Fabrication of sub-20 nm MoS₂ horizontal nanowire on silicon substrates by inclusion of precursors into polystyrene-b-polyethylene oxide nanopatterns: Detailed structural investigation

Herein, we demonstrate the fabrication of sub-20 nm MoS₂ horizontal nanowire arrays on silicon substrates using a self-assembled block copolymer assisted in situ inclusion approach. Microphase separated long-range ordered polystyrene-b-polyethylene oxide (PS-b-PEO) block copolymer (BCP) line-space nanopatterns were achieved through thermo-solvent annealing. The patterns produced had long-range order and domain sizes > 1 μm. The BCP structures were lightly etched and modified by anhydrous ethanol to facilitate insertion of molybdenum precursor within the film maintaining the parent BCP arrangements. Horizontal ordered molybdenum oxide nanowire arrays were then fabricated by ultraviolet (UV)/ozone treatment at room temperature. The oxides were converted to sulphides by thermal evaporation at different temperatures in Ar/H₂ environment. X-ray photoelectron spectroscopy revealed the composition and phases of the molybdenum oxide and sulphide nanowires. Elemental mapping was performed to investigate the interfaces between the oxide and sulphide nanowires with the substrate surface. The formation and stability of the sulphide nanowires were studied at different temperatures. The photoluminescence and Raman properties were studied at different formation temperatures to investigate defects and estimate the number of layers.